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authorEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
committerEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
commit7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 (patch)
tree3a7e8476e868ae15f4da1b7ce26b2db6f434468c /libm/double/chdtr.c
parentc117dd5fb183afb1a4790a6f6110d88704be6bf8 (diff)
Totally rework the math library, this time based on the MacOs X
math library (which is itself based on the math lib from FreeBSD). -Erik
Diffstat (limited to 'libm/double/chdtr.c')
-rw-r--r--libm/double/chdtr.c200
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diff --git a/libm/double/chdtr.c b/libm/double/chdtr.c
deleted file mode 100644
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--- a/libm/double/chdtr.c
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-/* chdtr.c
- *
- * Chi-square distribution
- *
- *
- *
- * SYNOPSIS:
- *
- * double df, x, y, chdtr();
- *
- * y = chdtr( df, x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns the area under the left hand tail (from 0 to x)
- * of the Chi square probability density function with
- * v degrees of freedom.
- *
- *
- * inf.
- * -
- * 1 | | v/2-1 -t/2
- * P( x | v ) = ----------- | t e dt
- * v/2 - | |
- * 2 | (v/2) -
- * x
- *
- * where x is the Chi-square variable.
- *
- * The incomplete gamma integral is used, according to the
- * formula
- *
- * y = chdtr( v, x ) = igam( v/2.0, x/2.0 ).
- *
- *
- * The arguments must both be positive.
- *
- *
- *
- * ACCURACY:
- *
- * See igam().
- *
- * ERROR MESSAGES:
- *
- * message condition value returned
- * chdtr domain x < 0 or v < 1 0.0
- */
- /* chdtrc()
- *
- * Complemented Chi-square distribution
- *
- *
- *
- * SYNOPSIS:
- *
- * double v, x, y, chdtrc();
- *
- * y = chdtrc( v, x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns the area under the right hand tail (from x to
- * infinity) of the Chi square probability density function
- * with v degrees of freedom:
- *
- *
- * inf.
- * -
- * 1 | | v/2-1 -t/2
- * P( x | v ) = ----------- | t e dt
- * v/2 - | |
- * 2 | (v/2) -
- * x
- *
- * where x is the Chi-square variable.
- *
- * The incomplete gamma integral is used, according to the
- * formula
- *
- * y = chdtr( v, x ) = igamc( v/2.0, x/2.0 ).
- *
- *
- * The arguments must both be positive.
- *
- *
- *
- * ACCURACY:
- *
- * See igamc().
- *
- * ERROR MESSAGES:
- *
- * message condition value returned
- * chdtrc domain x < 0 or v < 1 0.0
- */
- /* chdtri()
- *
- * Inverse of complemented Chi-square distribution
- *
- *
- *
- * SYNOPSIS:
- *
- * double df, x, y, chdtri();
- *
- * x = chdtri( df, y );
- *
- *
- *
- *
- * DESCRIPTION:
- *
- * Finds the Chi-square argument x such that the integral
- * from x to infinity of the Chi-square density is equal
- * to the given cumulative probability y.
- *
- * This is accomplished using the inverse gamma integral
- * function and the relation
- *
- * x/2 = igami( df/2, y );
- *
- *
- *
- *
- * ACCURACY:
- *
- * See igami.c.
- *
- * ERROR MESSAGES:
- *
- * message condition value returned
- * chdtri domain y < 0 or y > 1 0.0
- * v < 1
- *
- */
-
-/* chdtr() */
-
-
-/*
-Cephes Math Library Release 2.8: June, 2000
-Copyright 1984, 1987, 2000 by Stephen L. Moshier
-*/
-
-#include <math.h>
-#ifdef ANSIPROT
-extern double igamc ( double, double );
-extern double igam ( double, double );
-extern double igami ( double, double );
-#else
-double igamc(), igam(), igami();
-#endif
-
-double chdtrc(df,x)
-double df, x;
-{
-
-if( (x < 0.0) || (df < 1.0) )
- {
- mtherr( "chdtrc", DOMAIN );
- return(0.0);
- }
-return( igamc( df/2.0, x/2.0 ) );
-}
-
-
-
-double chdtr(df,x)
-double df, x;
-{
-
-if( (x < 0.0) || (df < 1.0) )
- {
- mtherr( "chdtr", DOMAIN );
- return(0.0);
- }
-return( igam( df/2.0, x/2.0 ) );
-}
-
-
-
-double chdtri( df, y )
-double df, y;
-{
-double x;
-
-if( (y < 0.0) || (y > 1.0) || (df < 1.0) )
- {
- mtherr( "chdtri", DOMAIN );
- return(0.0);
- }
-
-x = igami( 0.5 * df, y );
-return( 2.0 * x );
-}